There are many bacteria and viruses existing in daily environment, especially in hospitals, schools, and other public places. In addition, touch type electronic products are widely used nowadays and may become breeding grounds where bacteria and viruses are easily bred and propagated. In view of the aforesaid, it is required to use antimicrobial products having bacteriostatic and/or bactericidal activities to reduce breeding of microbes such as bacteria and viruses so as to improve living environments and to maintain health.
There are various antimicrobial products which have different antimicrobial mechanisms. Commercially available antimicrobial products are typically classified into three categories, i.e., natural antimicrobial agents, inorganic antimicrobial agents, and organic antimicrobial agents.
Specifically, the natural antimicrobial agents are produced by extracting specific ingredients from natural sources, such as chitin, mustard, wasabi, or the like. The natural antimicrobial agents have relatively pure components and may be conveniently used. However, they have a low sterilizing rate and a limited antimicrobial activity, and are also inferior in heat resistance such that they have short service life and thus may not be used for a long period of time.
The inorganic antimicrobial agents made from various metals (for example, silver, copper, or zinc), which are immobilized on a porous material via physical adsorption or ion exchange. For example, US 2014/0017462 discloses an antimicrobial glass article which comprises a glass substrate and copper-containing nanoparticles (such as Cu, CuO, or Cu2O nanoparticles) on a surface of the glass substrate. However, the appearance of the product such as the antimicrobial glass article may be undesirably tainted by the intrinsic color of the metal or metal ion. In addition, although silver ions have a superior antimicrobial effect and are most popularly used in the inorganic antimicrobial agents, they are costly and are liable to discoloration due to oxidation of the silver ions in use.
The organic antimicrobial agents include acylanilides, quaternary ammonium salts, phenols, and the like. The antimicrobial mechanism for the quaternary ammonium salts involves taking the advantage of easy combination of the positive charged ammonium ions contained in the quaternary ammonium salts with the negatively charged microbes so as to disrupt cell walls and/or cell membranes of the microbes, thus achieving an effect of killing or inhibiting the microbes. For example, it is described in the background of U.S. Pat. No. 5,959,014 that the antimicrobial agent having a quaternary ammonium group is synthesized by subjecting dimethylalkyl tertiary amine and chloropropyl trimethoxysilane to a reaction. The mechanism of the reaction is shown below:

However, since the antimicrobial agent contains chloride ions, it is liable to production of toxic chlorine gas when the antimicrobial agent is used at an elevated temperature. The chlorine gas is not only strongly hazardous to human health but also liable to production of oncogenic organic chloride, such as trichloromethane.
It is described in an article entitled “Process and Mechanism of Surface Modification of Silica with Silane Coupling Agent APTS” by Bing Qiao et al., Department of Chemical Engineering, Tsinghua University, Beijing, China, in CIESC Journal (July 2014) to modify surface of silica using gamma aminopropyltriethoxysilane (APTS). It is disclosed in the article that APTS may be subject to a hydrolysis in the presence of water which is followed by a condensation reaction to form a polysiloxane, as shown below.

It is desirable in the art to provide an antimicrobial agent which may be easily synthesized, which does not contain chloride ions, and which possesses superior antimicrobial activity.